GRE Math : How to find out when an equation has no solution

Study concepts, example questions & explanations for GRE Math

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Example Questions

Example Question #11 : Linear / Rational / Variable Equations

Quantity A: 

Quantity B: 

Possible Answers:

Quantity A is greater.

The relationship cannot be determined.

The two quantities are the same.

Quantity B is greater.

Correct answer:

Quantity A is greater.

Explanation:

To solve this problem, expand each function described by Quantities A and B:

Quantity A: 

Quantity B: 

Now note that Quantities A and B only differ in that Quantity A is greater by .

Since we are told that  is greater than  and thus always positive, Quantity A must be greater than Quantity B for all possible values of .

Example Question #51 : Gre Quantitative Reasoning

Quantity A: 

Quantity B: 

Possible Answers:

The two quantities are equal.

Quantity A is greater.

Quantity B is greater.

The relationship cannot be determined.

Correct answer:

Quantity A is greater.

Explanation:

Rather than manually finding common denominators and adding the fractions together, realize that

Since

Quantity A must be greater, and this can be seen without actually calculating its value.

Example Question #52 : Gre Quantitative Reasoning

Gre chart

Approximately, what was the percent growth of Beetleton's GDP from 2009 to 2010?

Possible Answers:

Correct answer:

Explanation:

Percent growth is given as:

For Beetleton, this can be expressed as (in terms of billions of US dollars):

Example Question #53 : Gre Quantitative Reasoning

The sum of two integers is . The larger integer is  greater than the smaller integer. What is the positive difference between the two?

Possible Answers:

Correct answer:

Explanation:

Let us write down what we are told in mathematical terms, designating the smaller integer as  and the larger integer as .

The sum of the two integers is :

And the larger integer is % greater than the smaller integer:

Writing the first equation in terms of  gives:

Which allows us to find :

Thus, the positive difference between the two is found as

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